A conventional air conditioner is disclosed in a patent document 1. This air conditioner includes an indoor apparatus disposed indoors and an outdoor apparatus disposed outdoors. The outdoor apparatus is provided with a compressor, an outdoor heat exchanger, and an outdoor fan, while the indoor apparatus is provided with an indoor heat exchanger and an indoor fan. The compressor flows a refrigerant to operate a refrigeration cycle.
A refrigerant outlet portion of the compressor is connected to one end of the indoor heat exchanger and one end of the outdoor heat exchanger via a four-way valve by means of a refrigerant pipe. The other ends of the indoor heat exchanger and outdoor heat exchanger are connected to each other via an expansion valve by means of the refrigerant pipe. The outdoor fan is disposed to oppose the outdoor heat exchanger and prompts a heat exchange between the outdoor heat exchanger and outdoor air. The indoor fan introduces indoor air into the indoor apparatus and sends the air, performing the heat exchange with the indoor heat exchanger, into a room.
During a warming operation time, the refrigerant output from the compressor thanks to switching of the four-way valve flows through the indoor heat exchanger, the expansion valve, the outdoor heat exchanger and returns to the compressor. In this way, the indoor heat exchanger forms a high temperature portion of the refrigeration cycle, while the outdoor heat exchanger forms a low temperature portion of the refrigeration cycle. The indoor air rises in temperature thanks to the heat exchange with the indoor heat exchanger and is sent into the room, whereby the indoor warming is performed. During this time, the indoor heat exchanger performs the heat exchange with the indoor air; as a result of this, the indoor heat exchanger becomes low in temperature, while the outdoor heat exchanger performs the heat exchange with outdoor air to be raised in temperature thanks to driving of the outdoor fan.
During a cooling operation time, the refrigerant output from the compressor thanks to the switching of the four-way valve flows in a direction opposite to the direction during the warming operation time. In other words, the refrigerant flows through the outdoor heat exchanger, the expansion valve, the indoor heat exchanger and returns to the compressor. In this way, the outdoor heat exchanger forms the high temperature portion of the refrigeration cycle, while the indoor heat exchanger forms a low temperature portion of the refrigeration cycle. The indoor air falls in temperature thanks to the heat exchange with the indoor heat exchanger and is sent into the room, whereby the indoor cooling is performed. During this time, the indoor heat exchanger performs the heat exchange with the indoor air; as a result of this, the indoor heat exchanger becomes rises in temperature, while the outdoor heat exchanger performs the heat exchange with outdoor air to be lowered in temperature thanks to driving of the outdoor fan.
Besides, if the outdoor heat exchanger has frost during the warming operation time, a defrosting operation is performed. During a defrosting operation time, the indoor fan and the outdoor fan are stopped, and the refrigerant flows in the same direction as the direction during the cooling operation time thanks to the switching of the four-way valve. In this way, the outdoor heat exchanger forms a high temperature portion of the refrigeration cycle, accordingly, it is possible to defrost the outdoor heat exchanger.